I am wondering if anyone here has tried out these gizmos--the headstock ones that are mounted under the tuners--and found them to have significant sustain improving qualities at volume (or lower vol). A friend of mine was talking with David Gilmore before his show and when he asked how Gil obtained his legendary sustain Gilmore went over and showed him the back of his guitars, which were equipped with Fathead sustain plates. They are no longer made, so they are a PIA to find (unless someone knows a new production). Whatdya say?
You might find a Fatfinger simpler.
http://www.musiciansfriend.com/accessor ... n-enhancer